The Anus: Gastrointestle Analysis
The anus is a short complex termination of the gastrointestinal tract. Macroscopically it is composed of the anal canal, anal verge, and anal margin. Surrounding these structures is a group of muscles that are essential for maintenance of fecal continence, and injuries to this complex area can lead to devastating consequences. The anal canal anatomically extends from the dentate line to the anal verge. Functionally, however, extends from the proximal aspect of the internal anal sphincter (IAS)/levator ani muscle to the anal verge, a length of approximately 4 cm. The anal canal includes the dentate line and is surrounded by the IAS and external anal sphincter (EAS) (Thompson-Fawcett et al., 1998).